Carmilla
But dreams come through stone walls, light up dark rooms, or darken light ones, and their persons make their exits and their entrances as they please, and laugh at locksmiths. Before there was Dracula, there was Carmilla. A short 1872 novel by Irish author Joseph Thomas Sheridan Le Fanu, Carmilla is an important contribution to classic horror, both by being an early work of vampire fiction, and for featuring a lesbian vampire at that! It's an extremely fast read, so I guess it's fitting that it has a disappointingly abrupt ending to match that brisk pace. I appreciate its audacity, and I recommend it more for its historical significance than my enjoyment from reading it.